Alliance seeks 36 percent cut in Pleasant Bay nitrogen

Monday

May 22, 2017 at 6:50 AM

By Rich Eldred reldred@wickedlocal.com

Rather than going it alone the Pleasant Bay Alliance pursuing wastewater reform on a collective front.

Pleasant Bay receives groundwater from Orleans, Brewster, Harwich and Chatham, all members of the Alliance. The goal is to clean up the 21,600-acre bay by alleviating controllable excess levels of nitrogen that arrive in it through the groundwater, primarily from septic systems (75 percent) but also fertilizers (16 percent) and surface runoff (9 percent). There are uncontrolled sources as well.

The alliance has just issued a lengthy Composite Nitrogen Management Analysis and Director Carole Ridley was in Brewster to discuss it with the selectmen on Monday night. She brought reinforcements, including Brian Dudley from the Massachusetts Department of Environmental Protection.

The composite analysis was designed to show the effect of the four individual towns' current plans to restrict nitrogen in the bay. Looking at the total effect, the towns could then choose to modify their plans if they wish.

To reach the desired conditions the amount of nitrogen filtering into the bay must be reduced by 17,717 kilograms a year, a 36 percent reduction bay-wide. Pleasant Bay is divided into smaller sub-embayments, which have their own requirements ranging from no reduction at all in Crow’s Pond in Chatham to 83 percent removal in Meetinghouse Pond in Orleans, which is at the far narrow end of the bay. Those reflect the current status – any additional development around the bay would require 100 percent of its nitrogen to be removed.

While the above figures reflect the state of the bay as a whole, six sub-embayments account for 71 percent of the total nitrogen input that needs elimination: Round Cove, Muddy Creek, Ryder’s Cove, Meetinghouse Pond, Pochet and Little Pleasant Bay.

“There are seven sub-embayments where one town is responsible for nitrogen removal,” Ridley noted. “There are 11 sub-embayments that are shared by more than one town. So each town is working separately on a plan even though this is very interrelated. The purpose of the composite analysis was to show the effect of the four town plans on nitrogen removal in the bay. We found that nitrogen thresholds are met by the four town plans in combination.”

Ridley noted that a quarter of the removal is slated to come from non-traditional technologies, such as shellfish filtration or barriers.

“This assumes that all non-traditional technologies other than sewers will work,” she said. “That has yet to be proven. It also assumes communities are diligent in making sure growth is taken into account and that each town agrees to remove an amount in proportion to their share of the attenuated load. That might be the basis for an intermunicipal agreement.”

These plans won’t fully take effect for decades, although the Muddy Creek Bridge and a few pilot programs represent first steps.

Natural processes, bogs, streams and salt marshes can remove 11 percent (6,000 kilograms) of the total nitrogen load each year. That leaves the remaining reduction of 17,717 kg to the towns, with the town-by-town breakdown of 2,262 kg for Brewster, 4.076 for Chatham, 4,399 for Harwich and 6,980 for Orleans.

Chatham is working on sewers and its nitrogen removal should exceed its share, so theoretically other towns could do a bit less and collectively the towns could hit their target. In fact, Chatham will remove 13,058 kg town wide although a lot of that was headed for Nantucket Sound not Pleasant Bay.

Orleans is targeting 6,974 kg a year, only 6 kg short of what it needs; Harwich exceeds its need with 4,540 kg targeted (an excess of 141) and Brewster is undershooting at 1,871 (390 less than its share). However, a watershed-wide approach would allow the towns to trade off on their requirements.

How close these plans come to targets depends on a variety of factors. Orleans is counting on reducing fertilizer use by 25 percent, Brewster by 50 percent. Will than happen and how can it be enforced? The effectiveness of shellfish filtration will depend on environmental factors beyond town control (disease, water temperatures etc.).

Dudley said the state is looking into awarding watershed permits for watershed wastewater management – whether they would be town by town or given collectively to an entity is undetermined. But he noted Pleasant Bay could be the first to receive one.

“In 2002 we recognized we were doing evaluation and analysis on a watershed basis and it only made sense to come up with a permitting process that would acknowledge that,” he said, “and to be able to cross town boundaries in order to get community partnerships together that would recognize advantages of working together, economies of scale all translating into cost savings and a more efficient way of moving forward.”

The recent approval at Chatham town meeting to let Harwich send East Harwich wastewater to the treatment plant in Chatham is such an example.

The full composite management report is available at Pleasantbay.org for interested parties.